1. Field of the Invention
The present invention generally relates to a position locating system. More specifically, the present invention relates to a position locating system, a terminal device, a control method for a terminal device, a control program for a terminal device, and a computer-readable record medium being configured to store a control program for a terminal device, with regards to positioning based on signals from positional information satellites.
2. Background Information
Heretofore, a position locating system wherein the current position of an SPS receiver is located by utilizing a satellite navigation system, for example, an SPS (Satellite positioning system) has been put into practical use. Herein, a so-called “assisted type” wherein the SPS receiver acquires aid information for the position location from external apparatuses by radio is extensively utilized. This type of structure is shown in Japanese Laid-Open Patent Publication JP-A-2002-228738, especially FIG. 1. JP-A-2002-228738 hereby incorporated by reference.
The above external apparatuses, however, are of a plurality of sorts and provide the aid information in conformity with different rules or protocols. Accordingly, even if the SPS receiver is constructed to be capable of acquiring the aid information from a certain specified external apparatus, there is sometimes a problem that when the SPS receiver leaves the service area of the external apparatus and enters the service area of an external apparatus of another sort, it cannot acquire the aid information. In contrast, when the SPS receiver includes constructions conforming to all the different individual external apparatuses, there is a problem in that a position locating chip becomes expensive.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved position locating system, a terminal device, a control method for a terminal device, a control program for a terminal device, and a computer-readable record medium being configured to store a control program for a terminal device, with regards to positioning based on signals from positional information satellites. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.